1. Field of the Invention
This invention relates to electrical telecommunications cable.
2. Description of Prior Art
Telecommunications cable is normally constructed with a core comprising one or more core units, each having a multiplicity of twisted units of conductors, each unit conventionally being a twisted pair of conductors. A core may be formed as a single core unit of twisted pairs. Care is taken, so far as is practicable, to ensure that pairs of equal or similar twist lays are separated from each other by other pairs. The reason for this arrangement is an attempt to maximize the communications performance of the cable, e.g. to lessen pair-to-pair capacitance unbalance, to reduce crosstalk between pairs, and to lower the coefficient of deviation of mutual capacitance of pairs in the cable. To reduce the pair-to-pair capacitance unbalance and to reduce cross-talk, suggestions have been made to move the conductor pairs relative to one another as they progress towards a stranding machine for stranding them into a core unit so that in the finished core unit, the conductor pairs change in relative positions and distances apart. In a suggested method for changing the relative positions of conductor pairs as they move towards the stranding machine, the conductor pairs enter a guide arrangement which comprises a system of horizontal guides movable horizontally and located in vertical tiered fashion. This method was first suggested by S. Norblad of Telefonaktiebolaget L. M. Ericsson, in a paper entitled "Capacitance Unbalance Telecommunications Networks" read before the International Wire and Cable Symposium in 1971. As a result of the use of this method, the conductor pairs obviously change positions and distances apart in the finished core and perhaps in a random manner.